Process for rendering cellulosic fibers flame resistant

ABSTRACT

CELLULOSIC FIBROUS MATERIALS, ESPECIALLY TEXTILE MATERIALS, CAN BE ADVANTAGEOUSLY RENDERED FLAME RESISTANT BY APPLYING TO THEM AN AQUEOUS PREPARATION OF CERTAIN PHOSPHORUS COMPOUNDS. THE PREPARATIONS HAVE A PH-VALUE BELOW 3 AND CONTAIN AT LEAST ONE COMPOUND OF THE FORMULA   R1-O-P(-O-R2)(=O)-CH2-CH(-X)-CO-NH-CH2-O-R   IN WHICH R REPRESENTS A HYDROGEN ATOM, AN ALKYL RADICAL OR ALKENYL RADICAL, R1 AND R2 EACH REPRESENTS AN ALKYL, HALOGENALKYL OR ALKENYL RADICAL CONTAINING UP TO 4 CARBON ATOMS AND X REPRESENTS A HYDROGEN OR HALOGEN ATOM, A METHYL GROUP OR A GROUP OF THE FORMULA   -CH2-CO-NH-CH2-O-R   WHERE R HAS THE ABOVE MEANING. THE MATERIAL SO TREATED MUST THEN BE DRIED, AND SUBJECTED TO A HEAT TREATMENT AT A TEMPERATURE ABOVE 100* C. TO ACHIEVE A FLAME-RESISTANT FINISH FAST TO WASHING IT IS NOT NECESSARY TO ADD AN AMINOPLAST TO THE AQUEOUS PREPARATION AS HAS BEEN GENERALLY DONE HERETOFORE. THE PRESENT FLAME-RESISTANT FINISH WILL WITHSTAND SEVERAL WASHES OR DRY CLEANING OPERATIONS AND THE TEXTILE MECHANICAL PROPERTIES SUCH AS TEAR STRENGTH WILL BE IMPAIRED BY VERY LITTLE.

6 rm. (:1. c093 /18; C09k 3/28 US. Cl. 117-136 7 Claims ABSTRACT OF THE DISCLOSURE Cellulosicfibrous materials, especially textile materials, can be advantageously rendered flame resistant by applying to them an aqueous preparation of certain phosphorus compounds. The preparations have a pH-value below 3 and contain at least one compound of the formula in which R represents a hydrogen atom, an alkyl radical or alkenyl radical, R and R each represents an alkyl, halogenalkyl or alkenyl radical containing up to 4 carbon atoms and X represents a hydrogen or halogen atom, a methyl group or a group of the formula where R has the above meaning.

The material so treated must then be dried, and subjected to a heat treatment at a temperature above 100 C. To achieve a flame-resistant finish fast to washing it is not necessary to add an aminoplast to the aqueous preparation as has been generally done heretofore. The present flame-resistant finish will withstand several washes or dry cleaning operations and the textile mechanical properties such as tear strength will be impaired but very little.

CROSS REFERENCES TO RELATED APPLICATIONS This a continuation-in-part of applicants copending application Ser. No. 640,518, filed May 23, 1967, now abandoned the disclosure of which is relied on and incorporated by reference in this application.

It has been found that cellulosic fibrous materials, especially textile materials, can be advantageously rendered ilam gresistant by applying to said materials an aqueous preparation having a pH-value below 3, containing at least one phosphorus compound of the formula Rg-O o in which R represents a hydrogen atom, an alkyl radical or alkenyl radical, R and R each represents an alkyl, halogenalkyl or alkenyl radical containing up to 4 carbon atoms, and X represents a hydrogen or halogen atom, a methyl group or a group of the formula (where R has the above meaning), whereupon the material is dried at a temperature up to 100 C. and subjected to a heat treatment at a temperature above 100 C.

3,577,270 tented May 4, 1971 Phosphorus compounds of the Formula 1, containing one or more than one carboxylic acid methylolamide group and a wide variety of substituents R and R are known (see, for example, British patent specification 1,011,572. Preferred compounds are those of the formula R O o in which R represents an alkyl or halogenalkyl radical, that is to say a chloralkyl or bromalkyl or chlorobromalkyl radical, or an alkenyl radical e.g. an allyl radical containing at most 4 carbon atoms, X has the above meaning and R stands for an alkyl radical with 1 to 4 carbon atoms, an allyl radical or preferably for a hydrogen atom.

Very suitable are phosphorus compounds of the forin which R and R have the meaning as defined before and X is a methyl group or preferably a hydrogen atom.

Among these compounds, those of the formula wherein R is a methyl or ethyl radical, are preferred.

Special mention in this series deserves the 3-(dimethylphosphono)-propionic acid methylolamide of the formula The present process is carried out with the use of aqueous preparations which contain compounds of the Formula 1 and whose pH value is preferably from 1.4 to 2.5. To achieve these values of below 3, a mineral acid such as sulphuric, nitric, hydrochloric or preferably orthophosphoric acid is added to the preparations. Instead of the acids themselves, especially hydrochloric acid, there may be used their compounds from which the corresponding acids are readily formed in water, by hydrolysis. As relevant examples there may be mentioned phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, thionylchloride, sulphurylchloride, cyanuric chloride, acetylchloride and chloracetylchloride. When these compounds are hydrolyzed, they ,furnish exclusively acid fission products, for example cyanuric acid and hydrochloric acid It may prove advantageous to use instead of one of the aforementioned strong acids acid mixtures corresponding to the hydrolysis products of one of the compounds just mentioned, thus, for instance, instead of hydrochloric acid alone a mixture of hydrochloric acid and orthophosphoric acid corresponding to phosphorus pentachloride, the two acids being advantageously used at a molecular ratio of 5:1.

Apart from the compounds of the Formula 1 and the additives needed to establish the requisite pH value the preparations to be used in the present process may contain further ingredients. It is possible to add an aminoplast, for example a possibly etherified methylolurea or methylolmelamine, but such addition is surprisingly unnecessary in the present process (which is performed at (a) 0.25 to of an alkaline earth metal salt of an a,;8-ethylenically unsaturated monocarboxylic acid,

(b) 0.25 to of an N-methylolamide or N-methylolamide ether of an a,p-ethylenically unsaturated monocarboxylic or dicarboxylic acid, and

(c) 99.5 to 60% of at least one further copolymerizable compound.

These copolymers and their manufacture are likewise known (see U.S. patent specification 3,288,740). The additional use of such a copolymer may have a beneficial effect upon the tear sterngth and abrasion fastness' of the fibrous materials treated.

As a further additive, which offers advantages in some cases, there may be mentioned a softening dressing agent,

for example an aqueous polyethylene emulsion or ethyl-..

ene-copolymer emulsion.

The amount of compounds of the Formula 1 added to the aqueous preparation is advantageously chosen so that 20 to thereofis deposited on the material under treatment, In this connection it must be borne in mind that commercial textile materials from native or regenerated cellulose are capable of absorbing from to of an aqueous preparation.

The amount of additive required to adjust the hydrogen ion concentration to a maximum value of 3 depends on the selected pH value itself and on the type of substance added; in each individual case there is a mandatory minimum. A certain excess over this minimum is in general beneficial. A large excess offers no advantage and may even be harmful. The preparations e.g. may contain 1 to 10, preferably 5 to-8% by weight calculated on the amount of the phosphorus compound present of orthophosphoric acid.

When a polymer of the indicated kind is further added to the preparation, it is advantageous to use a small quantity thereof, for Example 1 to 10% of the weight of the compound of the Formula 1. The same is true of a possibly added softener of which likewise 1 to 10% are indicated.

The preparation is applied in the known manner to the cellulosic fibrous material, for example linen, cotton, synthetics, spun rayon or blends of these materials and others, such as wool, polyamide fibres or polyester fibres. The process is preferably applied to piecegoods which are impregnated at room temperature on a conventional padder containing the preparation.

The impregnated fibrous material must then be dried, advantageously at a temperature of up to 100 C. It is then subjected to a dry heat treatment at a temperature above 100 C., for example from to 200 C. and preferably from to 180 C.; this heat treatment may be the shorter the higher the temperature used is. This heat treatment takes, for example, 2 to 6 minutes at a temperature from 150 to 180 C. Since during this treatment the methylol or methylol ether residues in the compounds of the Formula 1 are split, water or an alcohol is formed at the same time. It has been found that these volatile fission products must be'continuously removed from the material to ensure that the desired effect is obtained in full. The apparatus used for the heat treatment must, therefore, be selected accordingly. Good results are obtained with those apparatus in which the prescribed temperature is kept constant and fresh air is introduced continuously, while the air charged with the volatile substances formed is expelled. Such apparatus, for example so-called turbo-fixers or jet-fixers, are known.

Subsequent washing with an acid acceptor, preferably with aqueous sodium carbonate solution, for example at 40 C. up to the boiling temperature and for 3 to 10 minutes, is necessary in view of the strongly acidic reaction medium.

As mentioned above it is possible to achieve by the present process flame-resistant finishes which will withstand several washes or dry cleaning operations and that 7 do not impair too much the textile-mechanical properties of the material treated, especially when the abovementioned copolymers and softeners are additionally used.

With the present process it has also become possible to fix the phosphorus compounds either at a lower temperature or during a shorter time period than with known processes which use preparations having a pH-value above 3. At the preferred temperature of 150 to 180 C. the fixing time can e.g. be reduced to /s to /s. Moreover the present process solves the problem of dirtying the apparatus wherein the heat treatment is carried out. The amount of: unwanted deposit of phosphorus containing products on the apparatus can be reduced to an acceptable level by the present process as compared with known processes which always yield unwelcome dirt.

EXAMPLE 1 A mercerized and bleached cotton fabric is padded with an aqueous solution containing per litre 360 g. of 3-(dimethylphosphono)-propionic acid methylolamide, 2 g. of phosphorus trichloride and 40 g. of an aqueous polyethylene emulsion of 20% strength. The pH value of the padding solution is 1.6. The fabric is then expressed to a weight increase of 75%, dried at 60 to 70 C., and'then treated for 4 /2 minutes at C. in a turbofixer. Finally, it is washed in a boiling bath containing per litre 2 g. of anhydrous sodium carbonate for 5 minutes. The fabric thus treated is flame-resistant and remains so even after 5 washes for /2 hour at 95 C. in a washing liquor containing per litre 5 g. of soap and 2 g. of, anhydrous sodium carbonate.

Instead of phosphorus trichloride the padding liquor may contain per litre 1.5 g. of phosphorus pentachloride, or 2.2 g. of phosphorus oxychloride, or 2.6 g. of thionylchloride or 10.6 g. of hydrochloric acid of 33% strength, in which case the pH-values of the padding liquors vary from 1 to 2. The flame-resistant finishes thus obtained are likewise fast towashing."

EXAMPLE 2 An aqueous padding liquor containing per litre 360 g. of 3-(dimethylphosphono)-propionic acid methylolamide and 40 g. of an aqueous polyethylene emulsion of 20% strength is neutralized with sodium hydroxide so that its pH-valueis 7.0. Then hydrochloric acid is added until the pH-value drops to 1.4, for. which purpose 12.7 ml. of hydrochloric acid of 37.5% strength are required.

A mercerized, bleached cotton fabric is padded with this liquor to a weight increase of 75%, dried at 60 to 70 C. and then treated for 4 /2 minutes at 155 C. in a turbofixer or for 2 minutes at Cr in a jet-fixer. The fabric is then washed for 5 minutes in a boiling sodium carbonate solution of 0.2% strength, rinsed in cold water and once more dried. The fabric, which now has a flameresistant finish, retains it even after having been repeatedly washed.

Similar, good results are obtained when the amount of hydrochloric acid added to the padding liquor is only sufficient to lower the pH-value to 2.0 or. 3.0.

EXAMPLE 3 site pH-values instead of first neutralizing the padding liquor and then adding hydrochloric acid to it:

Addltlve Percent Value treated as indicated in the following table. Afterwards the nzso. 98 4.35 2,0 fabrics are washed in a first bath containing per litre 2 g.

62 of anhydrous sodium carbonate at 95 C. for 5 minutes. Cyannric chloride 16. 1 1.

Acetylehloride 6. 85 1.1 10 Finally, samplesof these fabrics are washed 10 times in 1 2 2 1 21 a washing machine containing per litre 5 g. of soap and g 1 2 0 2 g. of anhydrous sodium carbonate for 30 minutes at 2 boiling temperature. 1 2 1 Afterwards the flame-resistance is tested according to l g 1 9 15 DIN 53,906. The results are summarized in the following table:

Preparation N0. Heat-treatment 13 14 15 After First First 10 First 10 Test Mins. C wash washes wash washes wash washes 4 130 Flame resistance i i t f i 1 2 110 4 130 10.8 10.1 m m a: co or... length. in cm." 3, pg 3;; 3;; ,3 -3 g ,5 2 170 9.1 9.0 9.3 9.6 8.5 9.6

l seconds. NorE.+=non-infiammable; -=infiammable. EXAMPLE 4 Whereas the present preparation No. 13 yields a perma- The process described in Example 1 is performed with the use of the padding liquors Nos. 9 to 12:

Padding liquor N0.

Components 9 10 11 12 3(dirnethylphosphon0)-propi0nie acid methylol-amide, g./litre 360 360 360 360 Aqueous polyethylene emulsion of strength, g./litre 4O 40 40 40 Aqueous copolymer emulsion, g./litre 40 40 Solution of 15.6 parts of phosphorustrichloride in 84.4 parts of water, inl./l 12 12 6 6 pH-value 2. 1 2. 2 2. 3 2. 4

The aqueous copolymer emulsion used is a 27% emulsion of a polymer from 78 parts of acrylic acid-n-bntyl ester, 14.5 parts of vinylidenechloride, 7.0 parts of acrylic acid methylolarnide and 0.5 part of calcium acrylate.

The flame-resistant finishes obtained are quite fast to washing, especially when, as in Nos. 10 and 12, the copolymer is used additionally.

In comparative tests carried out as described above the drop in tear strength was measured; the results are summarized in the following table:

Cotton fabrics are padded with the use of preparations Nos. 13, 14 and 15 each containing 450 g./l. 3-(dimethylphosphono)-propionic acid methylolamide. As curing catalyst the preparations contain:

No. 13: 30 g./l. H PO (85%) No. 14: 4 g./l. NH Cl No. 15: 13.8 g./1. NH Cl.

6 Preparations Nos. 13 and 15 thus contain equimolar proportions of H PO and NH Cl.

The pH-valne of preparation No. 13 is 1.5, whereas preparations 14 and 15 have pH-values between 4 and 5. The fabrics are then expressed to a weight increase of dried at 80 C. for 30 minutes and then heatnent flame-proof-finish already at short curing times (4 minutes at C. or 15 seconds at C.), preparations Nos. 14 and 15 having a pH-value of above 3 yield flame-proof finishes only after a prolonged curing time (32 minutes at 130 C. or 2 minutes at 170 C.).

EXAMPLE 6 Cotton fabrics are padded with the use of preparations 16 and 17 each containing 350 g./1. of 3-(dimethylphosphono)-propionic acid methylolamide, 20 g./l. of an aqueous polyethylene emulsion 80 g./l. of pentamethylolmelamine-dimethylether.

As curing catalyst the preparations contain:

No. 16: 30 g./1. H PO (85%) N0. 17: 4 g./l. NH Cl The pH-value of preparations 16 and 17 is 1.5 and 5, respectively.

The fabrics are then expressed, dried and heat-treated as set forth in Example 5.

Afterwards the flame-resistance is tested according to DIN 53,906 after the first wash and after 50 washes in baths disclosed in Example 5.

Preparation N0. 16 yields a flame-proof finish which is permanent after 50 washes when the impregnated fabric is subjected to a heat-treatment for only 40 seconds at 170 C. To obtain the same permanent flame-proof finish with preparation No. 17 the heat-treatment at 170 C. lasts 3 minutes.

Preparation No. 17 after this heat-treatment deposits 1.11 g. of dirt on the apparatus, whereas preparation No. 16 deposits only 0.33 g. of dirt, that is about 30% of the dirt deposited by preparation No. 17.

Fabrics impregnated with present preparations No. 16

require a time for heat-treatment which is 4.5 times shortor than for fabrics impregnated with preparation No. 17 having a pH-value above 3. The prolonged heat-treatment required by preparation No. 17 results in a 3 to 4 times dirtier heat-treating apparatus than the short heat-treatment with present preparation No. 16.

'2 EXAMPLE '7 Cotton fabrics are padded with the use of preparations .hos. 18 to 21 having the following compositions:

Amounts in g./lv in preparation No.

1Hdunotliylphosphono)-propionlc acid I nn thylolmuide 400 400 450 no billitli lt'mun. 20 20 f i W pl] 4.7 2.2 48 t2 i AlllOUllt necessary to bring pH below 3.

The fabrics are expressed, dried and heat-treated and washed as set forth in Example 1. The flame resistance is then tested according to DIN 53,906 after the first wash, and after 3 and 5 washes, respectively. The results are set forth in the following table:

Flame-resistance I of fabrics treated with preparation l lo.

Trent luont- 18 19 2B 21 After first wash i After 8 washes After 5 washes in which R represents a member selected from the grou consisting of a hydrogen atom, an alkyl radical and a alltcnyl radical, R and R each represents a member selected from the group consisting of an alltyl, halog allryl and an alkenyl radical containing up to -i carbon. atoms, and X represents a member selected from the group consisting of a hydrogen atom, a halogen atom, a methyl group and a group of the formula where R has the above meaning, whereupon the material is dried at a temperature up to 100 {3. and subjected to a heat treatment at a temperature above 100 C.

Process according to claim it wherein a pliOSpiltlt'tlS compound is employed of the formula in which R represents a member selected from the group consisting of a hydrogen atom, an alltyl radical "with to 4 carbon atoms and an allyl radical, lt represents a member selected from the group consisting of an alltyl,

- ialogenalkyl and an alkenyl radical containing up to 4 carbon atoms, and X represents a member selected from the group consisting of a hydrogen atom, a halogen atom, a methyl group and a group of the formula 3. Process according to claim 1, wherein a phosphorus compound is employed of the formula It1-o o in which R represents a member selected from the groups consisting of a hydrogen atom, an alkyl radical with 1 to 4 carbon atoms and an allyl radical, R represents a member selected from the group consisting of an allcyl, halogenalkyl and a alkenyl radical containing up to 4 carbon atoms, and X, represents a member selected from the group consisting of a hydrogen atom and a methyl group.

t. Process according to claim 1, wherein a phosphorus compound is employed of the formula in which R is a methyl or ethyl radical.

55. Process according to claim 1, wherein the phosphorus compound employed is 3-(dimethylphosphono) propionic acid methylolamide.

n. Process according to claim 1 which comprises treating the materials with an aqueous preparation containing in addition to the phosphorus compound also 1 to 10% of the weight of the phosphorus compound of a copolymer, obtained by polymerization in aqueous emulsion from (a) 0.25 to 10% of an alkaline earth metal salt of an a-p-ethylenically unsaturated monocarboxylic acid,

(b) 0.25 to of member selected from the group consisting of an N-methylolamide of an a-fl-ethylenically unsaturated monocarboxylic acid, an N- methylolamide of an a-B-ethylenically unsaturated dicarboxylic acid, an N-methylolamide ether of an u-fiethylenically unsaturated monocarboxylic acid and an N-methylolamide ether of an a-fl-ethylenically unsaturated dicarboxylic acid, and

(c) 99.5 to of at least one further copolymerizaole compound.

7. Process according to claim 1, which comprises treating said materials with an aqueous preparation of the phosphorus compound having a pH-value from 1.4 to 2.5.

References Cited UNITED STATES PATENTS 11/1966 Maeder et a1. 26029.6 4/1968 Zahir 260--943X US. Cl. X.R. i17-143; 106--15 22 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 577 1 7 Dated May 4 1971 Inventor(s) Christian Guth et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, in the heading, after the names of the inventors insert assignors to CIBA Limited, Basel, Switzerland,

a company of Switzerland Signed and sealed this 12th day of October, 1971 (SEAL) Attest:

EDWARD M.FI..E1CHER,JR. Attesting Officer ROBERT GOT'ISCHALK Acting Commissioner of Patents 

